Antenna and methods of use for an implantable nerve stimulator

ABSTRACT

A pulse generator that includes a communications module is disclosed herein. The communication module includes a transceiver and an antenna circuit. The antenna circuit includes a first pathway having a capacitor and a second, parallel pathway including a capacitor, and a resistor, and a radiating element arranged in series. The antenna circuit is tuned to have a resonant frequency corresponding to a desired transmission frequency and a bandwidth corresponding to shifts in the resonant frequency arising from the implantation of the antenna.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/675,181, filed on Aug. 11, 2017, also issued as U.S. Pat. No.10,722,721 on Jul. 28, 2020 and entitled “Antenna and Methods of Use foran Implantable Nerve,” which is a continuation of U.S. application Ser.No. 15/407,745, filed on Jan. 17, 2017, also issued as U.S. Pat. No.9,770,596 on Sep. 26, 2017 and entitled “Antenna and Methods of Use foran Implantable Nerve Stimulator,” which is a continuation of U.S.application Ser. No. 14/993,009, filed on Jan. 11, 2016, also issued asU.S. Pat. No. 9,700,731 on Jul. 11, 2017, and entitled “Antenna andMethods of use for an Implantable Nerve Stimulator,” which is anon-provisional of and claims the benefit of priority of U.S.Provisional Application No. 62/101,782 filed on Jan. 9, 2015, andentitled “Antenna and Methods of use for an Implantable NerveStimulator,” the entirety of each of which is hereby incorporated byreference herein. The present application is related to U.S. ProvisionalPatent Application Nos. 62/038,122 filed on Aug. 15, 2014 and entitled“Devices and Methods for Anchoring of Neurostimulation Leads”;62/038,131, filed on Aug. 15, 2014 and entitled “External PulseGenerator Device and Associated Methods for Trial Nerve Stimulation”;62/041,611, filed on Aug. 25, 2014 and entitled “Electromyographic LeadPositioning and Stimulation Titration in a Nerve Stimulation System forTreatment of Overactive Bladder, Pain and Other Indicators”; U.S.Provisional Patent Application No. 62/101,888, filed on Jan. 9, 2015 andentitled “Electromyographic Lead Positioning and Stimulation Titrationin a Nerve Stimulation System for Treatment of Overactive Bladder”, U.S.Provisional Patent Application No. 62/101,899, filed on Jan. 9, 2015 andentitled “Integrated Electromyographic Clinician Programmer For Use Withan Implantable Neurostimulator;” U.S. Provisional Patent Application No.62/101,897, filed on Jan. 9, 2015 and entitled “Systems and Methods forNeurostimulation Electrode Configurations Based on Neural Localization;”U.S. Provisional Patent Application No. 62/101,666, filed on Jan. 9,2015 and entitled “Patient Remote and Associated Methods of Use With aNerve Stimulation System;” and U.S.

Provisional Patent Application No. 62/101,884, filed on Jan. 9, 2015 andentitled “Attachment Devices and Associated Methods of Use With a NerveStimulation Charging Device”; each of which is assigned to the sameassignee and incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE INVENTION

The present invention relates to neurostimulation treatment systems andassociated devices, as well as methods of treatment, implantation andconfiguration of such treatment systems.

BACKGROUND OF THE INVENTION

Treatments with implantable neurostimulation systems have becomeincreasingly common in recent years. While such systems have shownpromise in treating a number of conditions, effectiveness of treatmentmay vary considerably between patients. A number of factors may lead tothe very different outcomes that patients experience, and viability oftreatment can be difficult to determine before implantation. Forexample, stimulation systems often make use of an array of electrodes totreat one or more target nerve structures. The electrodes are oftenmounted together on a multi-electrode lead, and the lead implanted intissue of the patient at a position that is intended to result inelectrical coupling of the electrode to the target nerve structure,typically with at least a portion of the coupling being provided viaintermediate tissues. Other approaches may also be employed, forexample, with one or more electrodes attached to the skin overlying thetarget nerve structures, implanted in cuffs around a target nerve, orthe like. Regardless, the physician will typically seek to establish anappropriate treatment protocol by varying the electrical stimulationthat is applied to the electrodes.

Current stimulation electrode placement/implantation techniques andknown treatment setting techniques suffer from significantdisadvantages. The nerve tissue structures of different patients can bequite different, with the locations and branching of nerves that performspecific functions and/or enervate specific organs being challenging toaccurately predict or identify. The electrical properties of the tissuestructures surrounding a target nerve structure may also be quitedifferent among different patients, and the neural response tostimulation may be markedly dissimilar, with an electrical stimulationpulse pattern, frequency, and/or voltage that is effective to affect abody function for one patent may impose significant pain on, or havelimited effect for, another patient. Even in patients where implantationof a neurostimulation system provides effective treatment, frequentadjustments and changes to the stimulation protocol are often requiredbefore a suitable treatment program can be determined, often involvingrepeated office visits and significant discomfort for the patient beforeefficacy is achieved. While a number of complex and sophisticated leadstructures and stimulation setting protocols have been implemented toseek to overcome these challenges, the variability in lead placementresults, the clinician time to establish suitable stimulation signals,and the discomfort (and in cases the significant pain) that is imposedon the patient remain less than ideal. In addition, the lifetime andbattery life of such devices is relatively short, such that implantedsystems are routinely replaced every few years, which requiresadditional surgeries, patient discomfort, and significant costs tohealthcare systems.

Furthermore, current stimulation systems rely on wireless communicationto maintain control of the implantable neurostimulation system. Thiswireless communication is frequently performed using one or moreantennas. However, current antennas do not perform well under certaincircumstances, and particularly when the antenna is implanted within thebody of a patient. This leads to decreased ability to communicate withimplanted devices and difficulty in maintaining control of thosedevices.

The tremendous benefits of these neural stimulation therapies have notyet been fully realized. Therefore, it is desirable to provide improvedneurostimulation methods, systems and devices, as well as methods forimplanting and configuring such neurostimulation systems for aparticular patient or condition being treated. It would be particularlyhelpful to provide such systems and methods so as to improve ease of useby the physician in implanting and configuring the system, as well as toimprove patient comfort and alleviation of symptoms for the patient,and/or to provide a redesigned antenna to improve communications withthe implanted antenna.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present disclosure relates to a communication modulethat includes a transceiver and an antenna circuit. The antenna circuitcan have a first resonant frequency when the antenna circuit is notimplanted in a patient's body, a second resonant frequency when theantenna circuit is implanted in the patient's body, and a bandwidth. Thebandwidth of the antenna circuit can be sufficient that a transmissionfrequency is received at the antenna circuit at greater than thehalf-power point when the antenna circuit is in vivo, despitevariability imposed on the resonant frequency of the transmissionsystem. As the shift from the first resonant frequency to the secondresonant frequency varies from patient to patient based on implantationand/or tissue properties of the patient, such a bandwidth of the antennacircuit enables effective communication between implanted and externaldevices without custom tuning of the antenna circuit for a specificimplantation in a specific patient.

One aspect of the present disclosure relates to an implantableneurostimulator for delivering one or more electrical pulses to a targetregion within a patient's body according to a program received viawireless communication with an external device. The implantableneurostimulator can include a hermetic housing having an externalsurface comprising a biocompatible material that can be implanted withina body of a patient, a transceiver disposed within the housing andincluding a first lead and a second lead, and a communication antennacircuit disposed within the housing and coupled to the first lead andthe second lead, the antenna circuit having a first path and a secondpath parallel to the first path. In some embodiments, the first pathincludes a first capacitor, and the second path includes a secondcapacitor, a radiating element, and a resistor, wherein the secondcapacitor, the resistor, and the radiating element are arranged inseries.

In some embodiments, the antenna circuit includes a printed circuitboard (PCB), and in some embodiments, the radiating element can includea plurality of conductive loops of the PCB, which plurality ofconductive loops can be located along and/or within a common plane ofthe PCB. In some embodiments, the conductive loops can include coppertraces embedded onto a substrate surface of the PCB, which copper tracescan produce an electric field dipole having a donut pattern with amaximum strength in the common plane, and which maximum field issubstantially normal to a body surface of the patient when the housingis implanted. In some embodiments, the plurality of loops include afirst loop and a second loop, which second loop can be located withinthe first loop.

In some embodiments of the implantable neurostimulator, the antennacircuit has a fixed natural resonant frequency, the first capacitor hasa first fixed capacitance and the second capacitor has a second fixedcapacitance. In some embodiments, the antenna circuit is defined by a Qfactor and the resistor is configured to diminish the Q factor of theantenna circuit. In some embodiments, the housing includes at least aceramic case portion so as to provide an efficient radio frequencytransparent window for wireless communication between the implantableneurostimulator and the external device, which the external device caninclude a clinician programmer, patient remote, or a charging device.

One aspect of the present disclosure relates to an implantableneurostimulator for delivering one or more electrical pulses to a targetregion within a patient's body. The implantable neurostimulator includesa hermetic and at least partially ceramic housing having an externalsurface that can be implanted within a body of a patient, an antennacircuit defined by a Q factor disposed within the housing and that canwirelessly communicate with an external device, and a transceiverdisposed within the housing and coupled to the antenna circuit. In someembodiments, the Q factor of the antenna circuit is limited ordiminished at a target frequency by a first resistor included in theantenna circuit.

In some embodiments, the first resistor increases a bandwidth of theantenna circuit. In some embodiments, the target frequency is between350 and 450 Hz, and in some embodiments, the target frequency isapproximately 403 Hz. In some embodiments, the second resistor isselected so that the bandwidth of the antenna circuit is between 5 Hzand 30 Hz, such bandwidth often being greater than 10 Hz or even 15 Hz,and in some embodiments, the bandwidth of the antenna circuit isapproximately 16 Hz.

In some embodiments, the antenna circuit includes a first capacitorarranged in parallel with a second capacitor, a radiating element, andthe first resistor. In some embodiments, the antenna circuit includes aprinted circuit board (PCB), the radiating element includes a pluralityof conductive loops on a surface of a substrate of the PCB, and theplurality of conductive loops are located within a common plane on thePCB. In some embodiments, the plurality of loops includes a first loopand a second loop, which second loop is located within the first loop.In some embodiments, the first capacitor has a first fixed capacitance,and the second capacitor has a second fixed capacitance.

One aspect of the present disclosure relates to an implantableneurostimulator for delivering one or more electrical pulses to a targetregion within a patient's body. The implantable neurostimulator includesan at least partially ceramic housing having an external surface thatcan be implanted within a body of a patient, a radio frequencytransceiver disposed within the ceramic housing and having a first leadand a second lead, and an antenna circuit disposed within the ceramichousing and configured to wirelessly communicate with an externaldevice, the antenna circuit coupled to the first lead and the secondlead and having a first path and a second path parallel to the firstpath. In some embodiments, the first path includes a first capacitor andthe second path includes a resonant tuned (RLC) circuit. In someembodiments, the antenna circuit has a fixed resonant frequency.

In some embodiments, the antenna circuit includes a printed circuitboard (PCB), and in some embodiments, the radiating element includes aplurality of conductive loops formed on the PCB, which plurality ofloops include a first loop, and a second loop, which second loop islocated within the first loop. In some embodiments, the fixed resonantfrequency corresponds to a transmitting frequency at which theimplantable neurostimulator can receive one or more wirelesscommunications.

In some embodiments, the antenna circuit has a bandwidth, whichbandwidth of the antenna circuit is tuned such that an effectiveness ofthe antenna circuit at receiving the transmitting frequency does notdrop below a half-power point of the antenna when implanted within thebody of the patient.

One aspect of the present disclosure relates to a method of wirelesscommunication of data between an implantable neurostimulator and anexternal device. The method includes implanting the neurostimulator witha patient's body, which implantable neurostimulator can include ahermetic housing, a transceiver disposed within the housing, whichtransceiver can include a first lead and a second lead, and an antennacircuit disposed within the housing and coupleable to the first lead andthe second lead. In some embodiments, the antenna circuit can have afirst path and a second path parallel to the first path, which firstpath can include a first capacitor, and which second path can include asecond capacitor, a radiating element, and a resistor. In someembodiments, the second capacitor, the resistor, and the radiatingelement are arranged in series, and the antenna circuit has a resonantfrequency. In some embodiments, the method can include receiving datawirelessly transmitted from the external device at the implantableneurostimulator, which data is transmitted at a transmission frequencyand can control delivery of one or more electrical pulses to a targetregion within the patient's body.

In some embodiments of the method, implanting the neurostimulator intothe patient's body creates an effective resonant frequency of theantenna circuit based on one or more properties of a tissue of thepatient's body into which the neurostimulator is implanted. In someembodiments, the one or more properties of a tissue of the patient'sbody can include at least one of: a density, a hydration level, aresistance, an inductance, and a tissue type. In some embodiments, theantenna circuit can be tuned to have a bandwidth encompassing both theeffective resonant frequency and the transmission frequency.

In some embodiments, the antenna circuit can include a printed circuitboard (PCB), and in some embodiments, the radiating element can be aplurality of conductive loops formed on the PCB. In some embodiments,the plurality of loops include a first loop, and second loop, whichsecond loop can be located within the first loop.

One aspect of the present disclosure relates to a method ofmanufacturing a communication module for an implantable neurostimulatorfor wireless data communication from within a patient's body and anexternal device. The method includes selecting a transceiver, andconnecting the transceiver to an antenna circuit. In some embodiments,the antenna circuit can have a first resonant frequency when notimplanted in a patient's body, and a second resonant frequency whenimplanted in a patient's body. In some embodiments, the second resonantfrequency varies from patient to patient based on one or more tissuecharacteristics (type of tissue, tissue thickness, etc.) of the patient,the implant characteristics (location, depth, etc.), and/or the like. Insome embodiments, the antenna circuit can have a first path and a secondpath parallel to the first path, the first path including a firstcapacitor, and the second path including a second capacitor, a radiatingelement, and a resistor. In some embodiments, the resistor increases thebandwidth of the antenna circuit such that the bandwidth includes thetransmission frequency when the antenna is implanted in the patient'sbody.

In some embodiments, the bandwidth is between 5 Hz and 30 Hz, and insome embodiments, the bandwidth is approximately 16 Hz. In someembodiments, the antenna circuit includes a printed circuit board. Insome embodiments, the radiating element includes a plurality of loopsprinted on the printed circuit board, which plurality of loops includesa first loop and a second loop positioned within the first loop. In someembodiments, the first capacitor has a first fixed capacitance and thesecond capacitor has a second fixed capacitance

One aspect of the present disclosure relates to a method of wirelesscommunication of data between an implantable neurostimulator and anexternal device. The method includes implanting the neurostimulatorwithin a patient's body, the neurostimulator including an antennacircuit disposed within a housing and having a first path and a secondpath parallel to the first path. In some embodiments, the first path caninclude a first capacitor, the second path can include a secondcapacitor, a radiating element, and a resistor, which second capacitor,resistor, and radiating element are arranged in series such that theantenna circuit has a first resonant frequency prior to implantation. Insome embodiments, the antenna circuit and the external device togetherhave a second resonant frequency differing from the first resonantfrequency after implantation, the second resonant frequency being withinan implanted resonant frequency range encompassing patient-to-patientresonant frequency variability. In some embodiments, the method caninclude transmitting data wirelessly between the external device and theimplantable neurostimulator, which data is transmitted at a transmissionfrequency corresponding to the second resonant frequency. In someembodiments, the second resistor is sufficient to maintain the wirelessdata transmission above a half-power point of the antenna circuitthroughout the implanted resonant frequency range.

One aspect of the present disclosure relates to a neurostimulationsystem for delivering one or more electrical pulses to a target regionwithin a patient's body. The neurostimulation system includes: aneurostimulator and a charger. The neurostimulator can include ahermetic housing having an external surface. The housing can beimplantable within a body of a patient, and the housing can include aceramic transmission region. The neurostimulator can include: a firstantenna circuit positioned to wirelessly communicate with an externaldevice through the ceramic region; and a transceiver disposed within thehousing and coupled to the first antenna circuit. The charger caninclude a second antenna circuit having a first path and a second pathparallel to the first path. The first path can include a firstcapacitor, and the second path can include: a second capacitor; aradiating element; and a resistor. In some embodiments, the secondcapacitor, the resistor, and the radiating element are arranged inseries.

In some embodiments, both of the first antenna circuit and the secondantenna circuits comprise printed circuit boards (PCB). In someembodiments, at least one of the first radiating element or the secondradiating includes a plurality of conductive loops on the PCB, whichplurality of conductive loops are located along a common plane of thePCB. In some embodiments, the conductive loops include copper tracesembedded onto a substrate surface of the PCB. In some embodiments, thecopper traces can be laid-out to produce an electric field dipole havinga donut pattern with a maximum strength in the common plane such that amaximum field is substantially normal to a body surface of the patientwhen the housing is implanted for use.

In some embodiments, the plurality of loops includes a first loop and asecond loop, which second loop is located within the first loop. In someembodiments, the antenna circuit has a fixed natural resonant frequency,the first capacitor has a first fixed capacitance and the secondcapacitor has a second fixed capacitance. In some embodiments, theantenna circuit is defined by a Q factor and the resistor is selected todiminish the Q factor of the antenna circuit such that a bandwidth ofthe antenna circuits encompasses patient implantation-relatedvariability in resonant frequency when the antenna circuit is implantedin the patient body and communicates with the external device.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to necessarily limit the scope ofthe disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a nerve stimulation system, whichincludes a clinician programmer and a patient remote used in positioningand/or programming of both a trial neurostimulation system and apermanently implanted neurostimulation system, in accordance withaspects of the invention.

FIGS. 2A-2C show diagrams of the nerve structures along the spine, thelower back and sacrum region, which may be stimulated in accordance withaspects of the invention.

FIG. 3A shows an example of a fully implanted neurostimulation system inaccordance with aspects of the invention.

FIG. 3B shows an example of a neurostimulation system having a partlyimplanted stimulation lead and an external pulse generator adhered tothe skin of the patient for use in a trial stimulation, in accordancewith aspects of the invention.

FIG. 4 shows an example of a neurostimulation system having animplantable stimulation lead, an implantable pulse generator, and anexternal charging device, in accordance with aspects of the invention.

FIG. 5A-5C show detail views of an implantable pulse generator andassociated components for use in a neurostimulation system, inaccordance with aspects of the invention.

FIG. 6 shows a schematic illustration of one embodiment of thearchitecture of the IPG.

FIG. 7 shows a schematic illustration of one embodiment of thecommunication module.

FIG. 8 shows a schematic illustration of the communication module,including a circuit diagram of the antenna circuit.

FIG. 9A shows a perspective view of one embodiment of an antennaassembly.

FIG. 9B shows a top view of one embodiment of the antenna assembly.

FIG. 10 shows a depiction of the electric field dipole pattern createdby the antenna assembly depicted in FIGS. 9A and 9B.

FIG. 11 is a flowchart illustrating one embodiment of a process formanufacturing a communication module and for wireless communication ofdata between an implantable neurostimulator and an external device.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to neurostimulation treatment systems andassociated devices, as well as methods of treatment,implantation/placement and configuration of such treatment systems. Inone particular embodiment, the invention relates to sacral nervestimulation treatment systems configured to treat overactive bladder(“OAB”) and relieve symptoms of bladder related dysfunction. It will beappreciated however that the present invention may also be utilized forany variety of neuromodulation uses, such as fecal dysfunction, thetreatment of pain or other indications, such as movement or affectivedisorders, as will be appreciated by one of skill in the art.

I. Neurostimulation Indications

Neurostimulation (or neuromodulation as may be used interchangeablyhereunder) treatment systems, such as any of those described herein, canbe used to treat a variety of ailments and associated symptoms, such asacute pain disorders, movement disorders, affective disorders, as wellas bladder related dysfunction. Examples of pain disorders that may betreated by neurostimulation include failed back surgery syndrome, reflexsympathetic dystrophy or complex regional pain syndrome, causalgia,arachnoiditis, and peripheral neuropathy. Movement orders include muscleparalysis, tremor, dystonia and Parkinson's disease. Affective disordersinclude depressions, obsessive-compulsive disorder, cluster headache,Tourette syndrome and certain types of chronic pain. Bladder relateddysfunctions include but are not limited to OAB, urge incontinence,urgency-frequency, and urinary retention. OAB can include urgeincontinence and urgency-frequency alone or in combination. Urgeincontinence is the involuntary loss or urine associated with a sudden,strong desire to void (urgency). Urgency-frequency is the frequent,often uncontrollable urges to urinate (urgency) that often result invoiding in very small amounts (frequency). Urinary retention is theinability to empty the bladder. Neurostimulation treatments can beconfigured to address a particular condition by effectingneurostimulation of targeted nerve tissues relating to the sensoryand/or motor control associated with that condition or associatedsymptom.

In one aspect, the methods and systems described herein are particularlysuited for treatment of urinary and fecal dysfunctions. These conditionshave been historically under-recognized and significantly underserved bythe medical community. OAB is one of the most common urinarydysfunctions. It is a complex condition characterized by the presence ofbothersome urinary symptoms, including urgency, frequency, nocturia andurge incontinence. It is estimated that about 33 million Americanssuffer from OAB. Of the adult population, about 30% of all men and 40%of all women live with OAB symptoms.

OAB symptoms can have a significant negative impact on the psychosocialfunctioning and the quality of life of patients. People with OAB oftenrestrict activities and/or develop coping strategies. Furthermore, OABimposes a significant financial burden on individuals, their families,and healthcare organizations. The prevalence of co-morbid conditions isalso significantly higher for patients with OAB than in the generalpopulation. Co-morbidities may include falls and fractures, urinarytract infections, skin infections, vulvovaginitis, cardiovascular, andcentral nervous system pathologies. Chronic constipation, fecalincontinence, and overlapping chronic constipation occur more frequentlyin patients with OAB.

Conventional treatments of OAB generally include lifestyle modificationsas a first course of action. Lifestyle modifications include eliminatingbladder irritants (such as caffeine) from the diet, managing fluidintake, reducing weight, stopping smoking, and managing bowelregularity. Behavioral modifications include changing voiding habits(such as bladder training and delayed voiding), training pelvic floormuscles to improve strength and control of urethral sphincter,biofeedback and techniques for urge suppression. Medications areconsidered a second-line treatment for OAB. These includeanti-cholinergic medications (oral, transdermal patch, and gel) and oralbeta-3 adrenergic agonists. However, anti-cholinergics are frequentlyassociated with bothersome, systemic side effects including dry mouth,constipation, urinary retention, blurred vision, somnolence, andconfusion. Studies have found that more than 50% of patients stop usinganti-cholinergic medications within 90 days due to a lack of benefit,adverse events, or cost.

When these approaches are unsuccessful, third-line treatment optionssuggested by the American Urological Association include intradetrusor(bladder smooth muscle) injections of Botulinum Toxin (BoNT-A),Percutaneous Tibial Nerve Stimulation (PTNS) and Sacral NerveStimulation (SNM). BoNT-A (Botox®) is administered via a series ofintradetrusor injections under cystoscopic guidance, but repeatinjections of BoNT-A are generally required every 4 to 12 months tomaintain effect and BoNT-A may undesirably result in urinary retention.A number or randomized controlled studies have shown some efficacy ofBoNT-A in OAB patients, but long-term safety and effectiveness of BoNT-Afor OAB is largely unknown.

Alternative treatment methods, typically considered when the aboveapproaches prove ineffective, is neurostimulation of nerves relating tothe urinary system. Such neurostimulation methods include PTNS and SNM.PTNS therapy consists of weekly, 30-minute sessions over a period of 12weeks, each session using electrical stimulation that is delivered froma hand-held stimulator to the sacral plexus via the tibial nerve. Forpatients who respond well and continue treatment, ongoing sessions,typically every 3-4 weeks, are needed to maintain symptom reduction.There is potential for declining efficacy if patients fail to adhere tothe treatment schedule. Efficacy of PTNS has been demonstrated in a fewrandomized-controlled studies, however, long-term safety andeffectiveness of PTNS is relatively unknown at this time.

II. Sacral Neuromodulation

SNM is an established therapy that provides a safe, effective,reversible, and long-lasting treatment option for the management of urgeincontinence, urgency-frequency, and non-obstructive urinary retention.SNM therapy involves the use of mild electrical pulses to stimulate thesacral nerves located in the lower back. Electrodes are placed next to asacral nerve, usually at the S3 level, by inserting the electrode leadsinto the corresponding foramen of the sacrum. The electrodes areinserted subcutaneously and are subsequently attached to an implantablepulse generator (IPG), also referred to herein as an “implantableneurostimulator” or a “neurostimulator.” The safety and effectiveness ofSNM for the treatment of OAB, including durability at five years forboth urge incontinence and urgency-frequency patients, is supported bymultiple studies and is well-documented. SNM has also been approved totreat chronic fecal incontinence in patients who have failed or are notcandidates for more conservative treatments.

A. Implantation of Sacral Neuromodulation System

Currently, SNM qualification has a trial phase, and is followed ifsuccessful by a permanent implant. The trial phase is a test stimulationperiod where the patient is allowed to evaluate whether the therapy iseffective. Typically, there are two techniques that are utilized toperform the test stimulation. The first is an office-based proceduretermed the Percutaneous Nerve Evaluation (PNE) and the other is a stagedtrial.

In the PNE, a foramen needle is typically used first to identify theoptimal stimulation location, usually at the S3 level, and to evaluatethe integrity of the sacral nerves. Motor and sensory responses are usedto verify correct needle placement, as described in Table 1 below. Atemporary stimulation lead (a unipolar electrode) is then placed nearthe sacral nerve under local anesthesia. This procedure can be performedin an office setting without fluoroscopy. The temporary lead is thenconnected to an external pulse generator (EPG) taped onto the skin ofthe patient during the trial phase. The stimulation level can beadjusted to provide an optimal comfort level for the particular patient.The patient will monitor his or her voiding for 3 to 7 days to see ifthere is any symptom improvement. The advantage of the PNE is that it isan incision free procedure that can be performed in the physician'soffice using local anesthesia. The disadvantage is that the temporarylead is not securely anchored in place and has the propensity to migrateaway from the nerve with physical activity and thereby cause failure ofthe therapy. If a patient fails this trial test, the physician may stillrecommend the staged trial as described below. If the PNE trial ispositive, the temporary trial lead is removed and a permanentquadri-polar tined lead is implanted along with an IPG under generalanesthesia.

A staged trial involves the implantation of the permanent quadri-polartined stimulation lead into the patient from the start. It also requiresthe use of a foramen needle to identify the nerve and optimalstimulation location. The lead is implanted near the S3 sacral nerve andis connected to an EPG via a lead extension. This procedure is performedunder fluoroscopic guidance in an operating room and under local orgeneral anesthesia. The EPG is adjusted to provide an optimal comfortlevel for the patient and the patient monitors his or her voiding for upto two weeks. If the patient obtains meaningful symptom improvement, heor she is considered a suitable candidate for permanent implantation ofthe IPG under general anesthesia, typically in the upper buttock area,as shown in FIGS. 1 and 3A.

TABLE 1 Motor and Sensory Responses of SNM at Different Sacral NerveRoots Response Nerve Innervation Pelvic Floor Foot/calf/leg Sensation S2-Primary somatic “Clamp” * of anal Leg/hip rotation, Contraction of basecontributor of pudendal sphincter plantar flexion of entire of penis,vagina nerve for external foot, contraction of calf sphincter, leg, footS3 - Virtually all pelvic “bellows” ** of Plantar flexion of greatPulling in rectum, autonomic functions and perineum toe, occasionallyother extending forward striated mucle (levetor toes to scrotum or labiaani) S4 - Pelvic autonomic “bellows” ** No lower extremity Pulling inrectum and somatic; No leg pr motor stimulation only foot * Clamp:contraction of anal sphincter and, in males, retraction of base ofpenis. Move buttocks aside and look for anterior/posterior shortening ofthe perineal structures. ** Bellows: lifting and dropping of pelvicfloor. Look for deepening and flattening of buttock groove

In regard to measuring outcomes for SNM treatment of voidingdysfunction, the voiding dysfunction indications (e.g., urgeincontinence, urgency-frequency, and non-obstructive urinary retention)are evaluated by unique primary voiding diary variables. The therapyoutcomes are measured using these same variables. SNM therapy isconsidered successful if a minimum of 50% improvement occurs in any ofprimary voiding diary variables compared with the baseline. For urgeincontinence patients, these voiding diary variables may include: numberof leaking episodes per day, number of heavy leaking episodes per day,and number of pads used per day. For patients with urgency-frequency,primary voiding diary variables may include: number of voids per day,volume voided per void and degree of urgency experienced before eachvoid. For patients with retention, primary voiding diary variables mayinclude: catheterized volume per catheterization and number ofcatheterizations per day.

The mechanism of action of SNM is multifactorial and impacts theneuro-axis at several different levels. In patients with OAB, it isbelieved that pudendal afferents can activate the inhibitory reflexesthat promote bladder storage by inhibiting the afferent limb of anabnormal voiding reflex. This blocks input to the pontine micturitioncenter, thereby restricting involuntary detrusor contractions withoutinterfering with normal voiding patterns. For patients with urinaryretention, SNM is believed to activate the pudendal nerve afferentsoriginating from the pelvic organs into the spinal cord. At the level ofthe spinal cord, pudendal afferents may turn on voiding reflexes bysuppressing exaggerated guarding reflexes, thus relieving symptoms ofpatients with urinary retention so normal voiding can be facilitated. Inpatients with fecal incontinence, it is hypothesized that SNM stimulatespudendal afferent somatic fibers that inhibit colonic propulsiveactivity and activates the internal anal sphincter, which in turnimproves the symptoms of fecal incontinence patients. The presentinvention relates to a system adapted to deliver neurostimulation totargeted nerve tissues in a manner that disrupt, inhibit, or preventneural activity in the targeted nerve tissues so as to providetherapeutic effect in treatment of OAB or bladder related dysfunction.In one aspect, the system is adapted to provide therapeutic effect byneurostimulation without inducing motor control of the musclesassociated with OAB or bladder related dysfunction by the deliveredneurostimulation. In another aspect, the system is adapted to providesuch therapeutic effect by delivery of sub-threshold neurostimulationbelow a threshold that induces paresthesia and/or neuromuscular responseor to allow adjustment of neurostimulation to delivery therapy atsub-threshold levels.

B. Positioning Neurostimulation Leads with EMG

While conventional approaches have shown efficacy in treatment ofbladder related dysfunction, there exists a need to improve positioningof the neurostimulation leads and consistency between the trial andpermanent implantation positions of the lead.

Neurostimulation relies on consistently delivering therapeuticstimulation from a pulse generator, via one or more neurostimulationelectrodes, to particular nerves or targeted regions. Theneurostimulation electrodes are provided on a distal end of animplantable lead that can be advanced through a tunnel formed in patienttissue. Implantable neurostimulation systems provide patients with greatfreedom and mobility, but it may be easier to adjust theneurostimulation electrodes of such systems before they are surgicallyimplanted. It is desirable for the physician to confirm that the patienthas desired motor and/or sensory responses before implanting an IPG. Forat least some treatments (including treatments of at least some forms ofurinary and/or fecal dysfunction), demonstrating appropriate motorresponses may be highly beneficial for accurate and objective leadplacement while the sensory response may not be required or notavailable (e.g., patient is under general anesthesia).

Placement and calibration of the neurostimulation electrodes andimplantable leads sufficiently close to specific nerves can bebeneficial for the efficacy of treatment. Accordingly, aspects andembodiments of the present disclosure are directed to aiding andrefining the accuracy and precision of neurostimulation electrodeplacement. Further, aspects and embodiments of the present disclosureare directed to aiding and refining protocols for setting therapeutictreatment signal parameters for a stimulation program implementedthrough implanted neurostimulation electrodes.

Prior to implantation of the permanent device, patients may undergo aninitial testing phase to estimate potential response to treatment. Asdiscussed above, PNE may be done under local anesthesia, using a testneedle to identify the appropriate sacral nerve(s) according to asubjective sensory response by the patient. Other testing procedures caninvolve a two-stage surgical procedure, where a quadri-polar tined leadis implanted for a testing phase to determine if patients show asufficient reduction in symptom frequency, and if appropriate,proceeding to the permanent surgical implantation of a neuromodulationdevice. For testing phases and permanent implantation, determining thelocation of lead placement can be dependent on subjective qualitativeanalysis by either or both of a patient or a physician.

In exemplary embodiments, determination of whether or not an implantablelead and neurostimulation electrode is located in a desired or correctlocation can be accomplished through use of electromyography (“EMG”),also known as surface electromyography. EMG, is a technique that uses anEMG system or module to evaluate and record electrical activity producedby muscles, producing a record called an electromyogram. EMG detects theelectrical potential generated by muscle cells when those cells areelectrically or neurologically activated. The signals can be analyzed todetect activation level or recruitment order. EMG can be performedthrough the skin surface of a patient, intramuscularly or throughelectrodes disposed within a patient near target muscles, or using acombination of external and internal structures. When a muscle or nerveis stimulated by an electrode, EMG can be used to determine if therelated muscle is activated, (i.e. whether the muscle fully contracts,partially contracts, or does not contract) in response to the stimulus.Accordingly, the degree of activation of a muscle can indicate whetheran implantable lead or neurostimulation electrode is located in thedesired or correct location on a patient. Further, the degree ofactivation of a muscle can indicate whether a neurostimulation electrodeis providing a stimulus of sufficient strength, amplitude, frequency, orduration to affect a treatment regimen on a patient. Thus, use of EMGprovides an objective and quantitative means by which to standardizeplacement of implantable leads and neurostimulation electrodes, reducingthe subjective assessment of patient sensory responses.

In some approaches, positional titration procedures may optionally bebased in part on a paresthesia or pain-based subjective response from apatient. In contrast, EMG triggers a measureable and discrete muscularreaction. As the efficacy of treatment often relies on precise placementof the neurostimulation electrodes at target tissue locations and theconsistent, repeatable delivery of neurostimulation therapy, using anobjective EMG measurement can substantially improve the utility andsuccess of SNM treatment. The measureable muscular reaction can be apartial or a complete muscular contraction, including a response belowthe triggering of an observable motor response, such as those shown inTable 1, depending on the stimulation of the target muscle. In addition,by utilizing a trial system that allows the neurostimulation lead toremain implanted for use in the permanently implanted system, theefficacy and outcome of the permanently implanted system is moreconsistent with the results of the trial period, which moreover leads toimproved patient outcomes.

C. Example Embodiments

FIG. 1 schematically illustrates an exemplary nerve stimulation system,which includes both a trial neurostimulation system 200 and apermanently implanted neurostimulation system 100, in accordance withaspects of the invention. The EPG 80 and IPG 10 are each compatible withand wirelessly communicate with a clinician programmer 60 and a patientremote 70, which are used in positioning and/or programming the trialneurostimulation system 200 and/or permanently implanted system 100after a successful trial. As discussed above, the clinician programmercan include specialized software, specialized hardware, and/or both, toaid in lead placement, programming, re-programming, stimulation control,and/or parameter setting. In addition, each of the IPG and the EPGallows the patient at least some control over stimulation (e.g.,initiating a pre-set program, increasing or decreasing stimulation),and/or to monitor battery status with the patient remote. This approachalso allows for an almost seamless transition between the trial systemand the permanent system.

In one aspect, the clinician programmer 60 is used by a physician toadjust the settings of the EPG and/or IPG while the lead is implantedwithin the patient. The clinician programmer can be a tablet computerused by the clinician to program the IPG, or to control the EPG duringthe trial period. The clinician programmer can also include capabilityto record stimulation-induced electromyograms to facilitate leadplacement and programming. The patient remote 70 can allow the patientto turn the stimulation on or off, or to vary stimulation from the IPGwhile implanted, or from the EPG during the trial phase.

In another aspect, the clinician programmer 60 has a control unit whichcan include a microprocessor and specialized computer-code instructionsfor implementing methods and systems for use by a physician in deployingthe treatment system and setting up treatment parameters. The clinicianprogrammer generally includes a user interface which can be a graphicaluser interface, an EMG module, electrical contacts such as an EMG inputthat can couple to an EMG output stimulation cable, an EMG stimulationsignal generator, and a stimulation power source. The stimulation cablecan further be configured to couple to any or all of an access device(e.g., a foramen needle), a treatment lead of the system, or the like.The EMG input may be configured to be coupled with one or more sensorypatch electrode(s) for attachment to the skin of the patient adjacent amuscle (e.g., a muscle enervated by a target nerve). Other connectors ofthe clinician programmer may be configured for coupling with anelectrical ground or ground patch, an electrical pulse generator (e.g.,an EPG or an IPG), or the like. As noted above, the clinician programmercan include a module with hardware and computer-code to execute EMGanalysis, where the module can be a component of the control unitmicroprocessor, a pre-processing unit coupled to or in-line with thestimulation and/or sensory cables, or the like.

In some aspects, the clinician programmer is configured to operate incombination with an EPG when placing leads in a patient body. Theclinician programmer can be electronically coupled to the EPG duringtest simulation through a specialized cable set. The test simulationcable set can connect the clinician programmer device to the EPG andallow the clinician programmer to configure, modify, or otherwiseprogram the electrodes on the leads connected to the EPG.

The electrical pulses generated by the EPG and IPG are delivered to oneor more targeted nerves via one or more neurostimulation electrodes ator near a distal end of each of one or more leads. The leads can have avariety of shapes, can be a variety of sizes, and can be made from avariety of materials, which size, shape, and materials can be tailoredto the specific treatment application. While in this embodiment, thelead is of a suitable size and length to extend from the IPG and throughone of the foramen of the sacrum to a targeted sacral nerve, in variousother applications, the leads may be, for example, implanted in aperipheral portion of the patient's body, such as in the arms or legs,and can be configured to deliver electrical pulses to the peripheralnerve such as may be used to relieve chronic pain. It is appreciatedthat the leads and/or the stimulation programs may vary according to thenerves being targeted.

FIGS. 2A-2C show diagrams of various nerve structures of a patient,which may be used in neurostimulation treatments, in accordance withaspects of the invention. FIG. 2A shows the different sections of thespinal cord and the corresponding nerves within each section. The spinalcord is a long, thin bundle of nerves and support cells that extend fromthe brainstem along the cervical cord, through the thoracic cord and tothe space between the first and second lumbar vertebra in the lumbarcord. Upon exiting the spinal cord, the nerve fibers split into multiplebranches that innervate various muscles and organs transmitting impulsesof sensation and control between the brain and the organs and muscles.Since certain nerves may include branches that innervate certain organs,such as the bladder, and branches that innervate certain muscles of theleg and foot, stimulation of the nerve at or near the nerve root nearthe spinal cord can stimulate the nerve branch that innervate thetargeted organ, which may also result in muscle responses associatedwith the stimulation of the other nerve branch. Thus, by monitoring forcertain muscle responses, such as those in Table 1, either visually,through the use of EMG as described herein or both, the physician candetermine whether the targeted nerve is being stimulated. Whilestimulation at a certain threshold may trigger the noted muscleresponses, stimulation at a sub-threshold level may still providestimulation to the nerve associated with the targeted organ withoutcausing the corresponding muscle response, and in some embodiments,without causing any paresthesia. This is advantageous as it allows fortreatment of the condition by neurostimulation without otherwise causingpatient discomfort, pain or undesired muscle responses.

FIG. 2B shows the nerves associated with the lower back section, in thelower lumbar cord region where the nerve bundles exit the spinal cordand travel through the sacral foramens of the sacrum. In someembodiments, the neurostimulation lead is advanced through the foramenuntil the neurostimulation electrodes are positioned at the anteriorsacral nerve root, while the anchoring portion of the lead proximal ofthe stimulation electrodes are generally disposed dorsal of the sacralforamen through which the lead passes, so as to anchor the lead inposition. FIG. 2C shows detail views of the nerves of the lumbosacraltrunk and the sacral plexus, in particular, the S1-S5 nerves of thelower sacrum. The S3 sacral nerve is of particular interest fortreatment of bladder related dysfunction, and in particular OAB.

FIG. 3A schematically illustrates an example of a fully implantedneurostimulation system 100 adapted for sacral nerve stimulation.Neurostimulation system 100 includes an IPG implanted in a lower backregion and connected to a neurostimulation lead extending through the S3foramen for stimulation of the S3 sacral nerve. The lead is anchored bya tined anchor portion 30 that maintains a position of a set ofneurostimulation electrodes 40 along the targeted nerve, which in thisexample, is the anterior sacral nerve root S3 which enervates thebladder so as to provide therapy for various bladder relateddysfunctions. While this embodiment is adapted for sacral nervestimulation, it is appreciated that similar systems can be used intreating patients with, for example, chronic, severe, refractoryneuropathic pain originating from peripheral nerves or various urinarydysfunctions or still further other indications. Implantableneurostimulation systems can be used to either stimulate a targetperipheral nerve or the posterior epidural space of the spine.

Properties of the electrical pulses can be controlled via a controllerof the implanted pulse generator. In some embodiments, these propertiescan include, for example, the frequency, strength, pattern, duration, orother aspects of the electrical pulses. These properties can include,for example, a voltage, a current, or the like. This control of theelectrical pulses can include the creation of one or more electricalpulse programs, plans, or patterns, and in some embodiments, this caninclude the selection of one or more pre-existing electrical pulseprograms, plans, or patterns. In the embodiment depicted in FIG. 3A, theimplantable neurostimulation system 100 includes a controller in the IPGhaving one or more pulse programs, plans, or patterns that may bepre-programmed or created as discussed above. In some embodiments, thesesame properties associated with the IPG may be used in an EPG of apartly implanted trial system used before implantation of the permanentneurostimulation system 100.

FIG. 3B shows a schematic illustration of a trial neurostimulationsystem 200 utilizing an EPG patch 81 adhered to the skin of a patient,particularly to the abdomen of a patient, the EPG 80 being encasedwithin the patch. In one aspect, the lead is hardwired to the EPG, whilein another the lead is removably coupled to the EPG through a port oraperture in the top surface of the flexible patch 81. Excess lead can besecured by an additional adherent patch. In one aspect, the EPG patch isdisposable such that the lead can be disconnected and used in apermanently implanted system without removing the distal end of the leadfrom the target location. Alternatively, the entire system can bedisposable and replaced with a permanent lead and IPG. When the lead ofthe trial system is implanted, an EMG obtained via the clinicianprogrammer using one or more sensor patches can be used to ensure thatthe leads are placed at a location proximate to the target nerve ormuscle, as discussed previously.

In some embodiments, the trial neurostimulation system utilizes an EPG80 within an EPG patch 81 that is adhered to the skin of a patient andis coupled to the implanted neurostimulation lead 20 through a leadextension 22, which is coupled with the lead 20 through a connector 21.This extension and connector structure allows the lead to be extended sothat the EPG patch can be placed on the abdomen and allows use of a leadhaving a length suitable for permanent implantation should the trialprove successful. This approach may utilize two percutaneous incisions,the connector provided in the first incision and the lead extensionsextending through the second percutaneous incision, there being a shorttunneling distance (e.g., about 10 cm) there between. This technique mayalso minimize movement of an implanted lead during conversion of thetrial system to a permanently implanted system.

In one aspect, the EPG unit is wirelessly controlled by a patient remoteand/or the clinician programmer in a similar or identical manner as theIPG of a permanently implanted system. The physician or patient mayalter treatment provided by the EPG through use of such portable remotesor programmers and the treatments delivered are recorded on a memory ofthe programmer for use in determining a treatment suitable for use in apermanently implanted system. The clinician programmer can be used inlead placement, programming and/or stimulation control in each of thetrial and permanent nerve stimulation systems. In addition, each nervestimulation system allows the patient to control stimulation or monitorbattery status with the patient remote. This configuration isadvantageous as it allows for an almost seamless transition between thetrial system and the permanent system. From the patient's viewpoint, thesystems will operate in the same manner and be controlled in the samemanner, such that the patient's subjective experience in using the trialsystem more closely matches what would be experienced in using thepermanently implanted system. Thus, this configuration reduces anyuncertainties the patient may have as to how the system will operate andbe controlled such that the patient will be more likely to convert atrial system to a permanent system.

As shown in the detailed view of FIG. 3B, the EPG 80 is encased within aflexible laminated patch 81, which include an aperture or port throughwhich the EPG 80 is connected to the lead extension 22. The patch mayfurther an “on/off” button 83 with a molded tactile detail to allow thepatient to turn the EPG on and/or off through the outside surface of theadherent patch 81. The underside of the patch 81 is covered with askin-compatible adhesive 82 for continuous adhesion to a patient for theduration of the trial period. For example, a breathable strip havingskin-compatible adhesive 82 would allow the EPG 80 to remain attached tothe patient continuously during the trial, which may last over a week,typically two weeks to four weeks, or even longer.

FIG. 4 illustrates an example neurostimulation system 100 that is fullyimplantable and adapted for sacral nerve stimulation treatment. Theimplantable system 100 includes an IPG 10 that is coupled to aneurostimulation lead 20 that includes a group of neurostimulationelectrodes 40 at a distal end of the lead. The lead includes a leadanchor portion 30 with a series of tines extending radially outward soas to anchor the lead and maintain a position of the neurostimulationlead 20 after implantation. The lead 20 may further include one or moreradiopaque markers 25 to assist in locating and positioning the leadusing visualization techniques such as fluoroscopy. In some embodiments,the IPG provides monopolar or bipolar electrical pulses that aredelivered to the targeted nerves through one or more neurostimulationelectrodes, typically four electrodes. In sacral nerve stimulation, thelead is typically implanted through the S3 foramen as described herein.

In one aspect, the IPG is rechargeable wirelessly through conductivecoupling by use of a charging device 50 (CD), which is a portable devicepowered by a rechargeable battery to allow patient mobility whilecharging. The CD is used for transcutaneous charging of the IPG throughRF induction. The CD can either be either patched to the patient's skinusing an adhesive or can be held in place using a belt 53 or by anadhesive patch 52. The CD may be charged by plugging the CD directlyinto an outlet or by placing the CD in a charging dock or station 51that connects to an AC wall outlet or other power source.

The system may further include a patient remote 70 and clinicianprogrammer 60, each configured to wirelessly communicate with theimplanted IPG, or with the EPG during a trial. The clinician programmer60 may be a tablet computer used by the clinician to program the IPG andthe EPG. The device also has the capability to recordstimulation-induced electromyograms (EMGs) to facilitate lead placement,programming, and/or re-programming. The patient remote may be abattery-operated, portable device that utilizes radio-frequency (RF)signals to communicate with the EPG and IPG and allows the patient toadjust the stimulation levels, check the status of the IPG batterylevel, and/or to turn the stimulation on or off.

FIG. 5A-5C show detail views of the IPG and its internal components. Insome embodiments, the pulse generator can generate one or morenon-ablative electrical pulses that are delivered to a nerve to controlpain or cause some other desired effect, for example to inhibit,prevent, or disrupt neural activity for the treatment of OAB or bladderrelated dysfunction. In some applications, the pulses having a pulseamplitude in a range between 0 mA to 1,000 mA, 0 mA to 100 mA, 0 mA to50 mA, 0 mA to 25 mA, and/or any other or intermediate range ofamplitudes may be used. One or more of the pulse generators can includea processor and/or memory adapted to provide instructions to and receiveinformation from the other components of the implantableneurostimulation system. The processor can include a microprocessor,such as a commercially available microprocessor from Intel® or AdvancedMicro Devices, Inc.®, or the like. An IPG may include an energy storagefeature, such as one or more capacitors, and typically includes awireless charging unit.

One or more properties of the electrical pulses can be controlled via acontroller of the IPG or EPG. In some embodiments, these properties caninclude, for example, the frequency, strength, pattern, duration, orother aspects of the timing and magnitude of the electrical pulses.These properties can further include, for example, a voltage, a current,or the like. This control of the electrical pulses can include thecreation of one or more electrical pulse programs, plans, or patterns,and in some embodiments, this can include the selection of one or morepre-existing electrical pulse programs, plans, or patterns. In oneaspect, the IPG 100 includes a controller having one or more pulseprograms, plans, or patterns that may be created and/or pre-programmed.In some embodiments, the IPG can be programmed to vary stimulationparameters including pulse amplitude in a range from 0 mA to 10 mA,pulse width in a range from 50 μs to 500 μs, pulse frequency in a rangefrom 5 Hz to 250 Hz, stimulation modes (e.g., continuous or cycling),and electrode configuration (e.g., anode, cathode, or off), to achievethe optimal therapeutic outcome specific to the patient. In particular,this allows for an optimal setting to be determined for each patienteven though each parameter may vary from person to person.

As shown in FIGS. 5A-5B, the IPG may include a header portion 11 at oneend and a ceramic portion 14 at the opposite end. The header portion 11houses a feed through assembly 12 and connector stack 13, while theceramic case portion 14 houses an antennae assembly 16 to facilitatewireless communication with the clinician program, the patient remote,and/or a charging coil to facilitate wireless charging with the CD. Theremainder of the IPG is covered with a titanium case portion 17, whichencases the printed circuit board, memory and controller components thatfacilitate the electrical pulse programs described above. The ceramicportion 14 includes an end 22, sides 24, and a connection portion 26that connects the ceramic portion 14 to the case portion 17. In theexample shown in FIG. 5B, the antennae assembly 16 is positioned suchthat a plane 28 in which loops of a radiating element lay, isperpendicular to and extends through the sides 24 of the ceramic portion14.

In the example shown in FIG. 5C, the header portion of the IPG includesa four-pin feed-through assembly 12 that couples with the connectorstack 13 in which the proximal end of the lead is coupled. The four pinscorrespond to the four electrodes of the neurostimulation lead. In someembodiments, a Balseal® connector block is electrically connected tofour platinum/iridium alloy feed-through pins which are brazed to analumina ceramic insulator plate along with a titanium alloy flange. Thisfeed-through assembly is laser seam welded to a titanium-ceramic brazedcase to form a complete hermetic housing for the electronics. In someembodiments, some or all of the pieces of the IPG 10 forming thehermetic housing can be biocompatible, and specifically, can haveexternal surfaces made of biocompatible materials.

In some embodiment, such as that shown in FIG. 5A, the ceramic andtitanium brazed case is utilized on one end of the IPG where the ferritecoil and PCB antenna assemblies are positioned. A reliable hermetic sealis provided via a ceramic-to-metal brazing technique. The zirconiaceramic may comprise a 3Y-TZP (3 mol percent Yttria-stabilizedtetragonal Zirconia Polycrystals) ceramic, which has a high flexuralstrength and impact resistance and has been commercially utilized in anumber of implantable medical technologies. It will be appreciated,however, that other ceramics or other suitable materials may be used forconstruction of the IPG, and that ceramic may be used to form additionalportions of the case.

In one aspect, utilization of ceramic material provides an efficient,radio-frequency-transparent window for wireless communication with theexternal patient remote and clinician's programmer as the communicationantenna is housed inside the hermetic ceramic case. This ceramic windowhas further facilitated miniaturization of the implant while maintainingan efficient, radio-frequency-transparent window for long term andreliable wireless communication between the IPG and externalcontrollers, such as the patient remote and clinician programmer. TheIPG's wireless communication is generally stable over the lifetime ofthe device, unlike prior art products where the communication antenna isplaced in the header outside the hermetic case. The communicationreliability of such prior art devices tends to degrade due to the changein dielectric constant of the header material in the human body overtime.

In another aspect, the ferrite core is part of the charging coilassembly 15, shown in FIG. 5B, which is positioned inside the ceramiccase 14. The ferrite core concentrates the magnetic field flux throughthe ceramic case as opposed to the metallic case portion 17. Thisconfiguration maximizes coupling efficiency, which reduces the requiredmagnetic field and in turn reduces device heating during charging. Inparticular, because the magnetic field flux is oriented in a directionperpendicular to the smallest metallic cross section area, heatingduring charging is minimized. This configuration also allows the IPG tobe effectively charged at depth of 3 cm with the CD, when positioned ona skin surface of the patient near the IPG and reduces re-charging time.

FIG. 6 shows a schematic illustration of one embodiment of thearchitecture of the IPG 10 is shown. In some embodiments, each of thecomponents of the architecture of the IPG 10 can be implemented usingthe processor, memory, and/or other hardware component of the IPG 10. Insome embodiments, the components of the architecture of the IPG 10 caninclude software that interacts with the hardware of the IPG 10 toachieve a desired outcome, and the components of the architecture of theIPG 10 can be located within the housing.

In some embodiments, the IPG 10 can include, for example, acommunication module 600. The communication module 600 can be configuredto send data to and receive data from other components and/or devices ofthe exemplary nerve stimulation system including, for example, theclinician programmer 60 and/or the patient remote 70. In someembodiments, the communication module 600 can include one or severalantennas and software configured to control the one or several antennasto send information to and receive information from one or several ofthe other components of the IPG 10. While discussed herein in thecontext of the IPG 10, in some embodiments, the communication module 600as disclosed herein can be included in, for example, the charger 116.

The IPG 10 can further include a data module 602. The data module 602can be configured to manage data relating to the identity and propertiesof the IPG 10. In some embodiments, the data module can include one orseveral database that can, for example, include information relating tothe IPG 10 such as, for example, the identification of the IPG 10, oneor several properties of the IPG 10, or the like. In one embodiment, thedata identifying the IPG 10 can include, for example, a serial number ofthe IPG 10 and/or other identifier of the IPG 10 including, for example,a unique identifier of the IPG 10. In some embodiments, the informationassociated with the property of the IPG 10 can include, for example,data identifying the function of the IPG 10, data identifying the powerconsumption of the IPG 10, data identifying the charge capacity of theIPG 10 and/or power storage capacity of the IPG 10, data identifyingpotential and/or maximum rates of charging of the IPG 10, and/or thelike.

The IPG 10 can include a pulse control 604. In some embodiments, thepulse control 604 can be configured to control the generation of one orseveral pulses by the IPG 10. In some embodiments, for example, this canbe performed based on information that identifies one or several pulsepatterns, programs, or the like. This information can further specify,for example, the frequency of pulses generated by the IPG 10, theduration of pulses generated by the IPG 10, the strength and/ormagnitude of pulses generated by the IPG 10, or any other detailsrelating to the creation of one or several pulses by the IPG 10. In someembodiments, this information can specify aspects of a pulse patternand/or pulse program, such as, for example, the duration of the pulsepattern and/or pulse program, and/or the like. In some embodiments,information relating to and/or for controlling the pulse generation ofthe IPG 10 can be stored within the memory.

The IPG 10 can include a charging module 606. In some embodiments, thecharging module 606 can be configured to control and/or monitor thecharging/recharging of the IPG 10. In some embodiments, for example, thecharging module 606 can include one or several features configured toreceive energy for recharging the IPG 10 such as, for example, one orseveral inductive coils/features that can interact with one or severalinductive coils/features of the charger 116 to create an inductivecoupling to thereby recharge the IPG 10. In some embodiments, thecharging module 606 can include hardware and/or software configured tomonitor the charging of the IPG 10 including, for example, the chargingcoil assembly 15.

The IPG 10 can include an energy storage device 608. The energy storagedevice 608, which can include the energy storage features, can be anydevice configured to store energy and can include, for example, one orseveral batteries, capacitors, fuel cells, or the like. In someembodiments, the energy storage device 608 can be configured to receivecharging energy from the charging module 606.

FIG. 7 shows a schematic illustration of one embodiment of thecommunication module 600. The communication module 600 depicted in FIG.7 includes a transceiver 700 that is connected to an antenna circuit702, also referred to herein as a “communication antenna circuit,” thatincludes a radiating element 704.

The transceiver 700 can include a transmitter and a receiver that canshare common circuitry or a transmitter and receiver that do not sharecommon circuitry. The transceiver 700 can be connected to the antennacircuit 702 so as to transmit data and/or receive data via the antennacircuit 702. In some embodiments in which the charger 116 includes thecommunication module 600 in addition to the communication module 600located in the IPG 10, both the communication modules 600 of the charger116 and of the IPG 10 can include the antenna circuit 702.

The radiating element 704 can comprise a variety of shapes and sizes,and can be made from a variety of materials. In some embodiments, theradiating element 704 can comprise one or several loops of a conductivematerial such as, for example, copper, that together form an inductivecoil. The details of the radiating element 704 will be discussed atgreater length below.

FIG. 8 shows a schematic illustration of the communication module 600,including a circuit diagram of the antenna circuit 702. As seen in FIG.8, the transceiver 700 includes a first terminal 800 and a secondterminal 802 via which the transceiver 700 is connected to the antennacircuit 702. The antenna circuit 702 includes a first path 804 from thefirst terminal 800 to the second terminal 802, and a second path 806from the first terminal 800 to the second terminal 802. As seen in FIG.8, the first and second paths 804, 806 are parallel paths.

The antenna circuit 702 includes a first capacitor 808, a secondcapacitor 810, a resistor 812, and the radiating element 704. In someembodiments, one or several of the first capacitor 808, the secondcapacitor 810, the resistor 812, and the radiating element 704 can be inseries or in parallel with the others of the first capacitor 808, thesecond capacitor 810, the resistor 812, and the radiating element 704.In the embodiment depicted in FIG. 8, the first capacitor 808 is locatedin the first path 804 and is in parallel with the second capacitor 810,the resistor 812, and the radiating element 704 which are located in thesecond path 806, and which are in series. In some embodiments, thesecond capacitor 810, the resistor 812, and the radiating element 704form an RLC circuit.

In some embodiments, one or both of the first and second capacitor 808,810 can have a fixed capacitance, and in some embodiments, one or bothof the first and second capacitor 808, 810 can have a variableresistance. Similarly, in some embodiments, the resistor 812 can haveeither a fixed resistance or a variable resistance, and the radiatingelement 704 can have a fixed or variable inductance.

In some embodiments, the electrical properties of one or several of thefirst capacitor 808, the second capacitor 810, the resistor 812, and theradiating element 704 can be selected to achieve a desired tuning of theantenna circuit 702. This desired tuning can include, for example,tuning the antenna circuit 702 such that the antenna circuit 702 has adesired resonant frequency, which desired resonant frequency can, forexample, correspond to a desired frequency for data transmission, alsoreferred to herein as the “transmission frequency” or the “transmittingfrequency.” This resonant frequency can be fixed, or variable, and insome embodiments, this resonant frequency can be, for example, between200 Hz and 600 Hz, between 300 Hz and 500 Hz, between 350 Hz and 450 Hz,approximately 400 Hz, approximately 403 Hz, and/or any other orintermediate value or range. In some embodiments, the resonant frequencycan be such that the wavelength of a radio signal generated at theresonant frequency is longer than the longest dimension of the IPG 10.As used herein, “approximately” refers to 1%, 5%, 10%, 15%, 20%, or 25%of the therewith associated value or range.

In some embodiments in which the electrical properties of one or severalof the first capacitor 808, the second capacitor 810, the resistor 812,and the radiating element 704 are inconsistent between antenna circuits702 electrical properties of one or several of the others of the firstcapacitor 808, the second capacitor 810, the resistor 812, and theradiating element 704 may be adjusted to achieve the desired resonantfrequency of the antenna circuit 702. Such adjustment of the electricalproperties of one or several of the first capacitor 808, the secondcapacitor 810, the resistor 812, and the radiating element 704 can occurwhen the inductance of the radiating elements 704 is not consistentand/or fixed between radiating elements 704. This adjustment of theelectrical properties of one or several of the first capacitor 808, thesecond capacitor 810, and the resistor 812 in response to inconsistentinductance of radiating elements 704 can be time consuming and costly.

In one embodiments, the antenna circuit 702 can be formed on a printedcircuit board (PCB), and particularly, the one or several loops of theradiating element can be printed on and/or embedded in the PCB. Thisembedding of the one or several loops of the radiating element 704 inthe PCB can increase the increase the consistency of the inductance ofthe radiating elements 704 across several antenna circuits 702. Thisconsistency in the inductance across several radiating elements 704 canallow the use of first and second capacitors 808, 810 having fixedcapacitance and resistor 812 having a fixed resistance in the creationof the antenna circuit 702 and can eliminate the need for tuning of theantenna circuit via the adjustment of the electrical properties of oneor several of the first capacitor 808, the second capacitor 810, and theresistor 812.

In some embodiments, the antenna circuit 702 can be further tuned suchthat the antenna circuit 702 has a desired bandwidth. The bandwidth ofthe antenna circuit can be determined with a variety of knowntechniques, and in some embodiments can be defined as the range offrequencies within which the performance of the antenna, with respect tosome characteristic, conforms to a specified standard, and specificallythe range of frequencies over which the output power of the antennacircuit is greater than the half-power point, and thus is greater thanone-half of the mid-band value. In some embodiments, the antenna circuit702 can be tuned to have a desired bandwidth by the inclusion ofresistor 812 in the antenna circuit 702, and specifically by inclusionof resistor 812 have a desired resistance level in the antenna circuit702.

In some embodiments, the inclusion of resistor 812 can decrease the Qfactor of the antenna circuit 702, and can thus decrease the mid-bandvalue of the antenna circuit 702. However, this disadvantageous decreasein the Q factor can be offset by the benefit of the increased bandwidthof the antenna circuit 702. Specifically, the implantation of theantenna circuit 702 into the body of the patient can affect resonantfrequency of the antenna circuit 702. Thus, the antenna circuit 702 canhave a first resonant frequency when not implanted in a patient's body,and a second resonant frequency when implanted in the patient's body.Further, this second resonant frequency is not consistent betweenpatients, but rather varies based on one or several properties of thetissue into which the antenna circuit 702, including the antenna circuit702 in the IPG 10, is implanted. These properties of the tissue caninclude, for example, at least one of a density, a hydration level, aresistance, an inductance, and a tissue type.

While this effect of the implantation of the antenna circuit 702 on theresonant frequency varies from patient to patient, the bandwidth of theantenna circuit 702 can be tuned to include a large percentage of theexpected second frequencies of the antenna circuit 702. In someembodiments, this bandwidth can be, for example, between 1 Hz and 50 Hz,between 5 Hz and 30 Hz, between 10 Hz and 20 Hz, approximately 20 Hz,approximately 16 Hz, and/or any other or intermediate value or range.Thus, in such embodiments, the effectiveness of the antenna circuit 702at receiving the transmitting frequency does not drop below thehalf-power point when the antenna circuit 702 is implanted into apatient's body.

FIG. 9A shows a perspective view of one embodiment of an antennaassembly 900 and FIG. 9B shows a top view of one embodiment of theantenna assembly 900. The antenna assembly can be used in thecommunication module 600 of one or both the IPG 10 and the charger 116.In some embodiments, both the IPG 10 and the charger 116 can include theantenna assembly 900. The antenna assembly 900 includes a printedcircuit board (PCB) 902 upon which the first and second capacitors 808,810 and the first resistor 812 are mounted, and in which the radiatingelement 704 is embedded.

As specifically seen in FIGS. 9A and 9B, the radiating element 704comprises a plurality of loops, and specifically, a first loop 904 and asecond loop 906. In some embodiments, the radiating element can comprisea single copper trace formed and/or embedded in the PCB 902, whichsingle copper trace is shaped to create the first loop 904 and thesecond loop 906. In some embodiments, the first and second loops 904,906 can each comprise a copper trace formed and/or embedded in the PCB902. In some embodiments, the first and second loops 904, 906 can belocated in the same plane within the PCB 902. In some embodiments,placement of the first and second loops 904, 906 in the same planewithin the PCB 902 can be enabled by the placement of one of the loops904, 906 within the other of the loops 904, 906, and as shown in FIG.9A, by the placement of the second loop 906 within the first loop 904.

In some embodiments, the antenna assembly 900 can further include one orseveral spacers 908 and/or bumpers that can facilitate in properlypositioning the antenna assembly 900 within the IPG 10 and a connector,such as a flex-connector 910 that can be used to electrically connectthe antenna assembly 900 to other components of the IPG 10 such as, forexample, the transceiver 700.

In some embodiments, and as seen in FIG. 9B, the radiating element 704can include a necked down portion 920. The necked down portion 920 ofthe radiating element 704 can pass the resistor 812 without electricallyconnecting to the resistor 812. In some embodiments, the necked downportion 920 can be located relatively deeper in the PCB 902 than theresistor 812. In some embodiments, the necked down portion 920 and theother portions of the radiating element 704 can be located at the samedepth in the PCB 902, in a common plane that is relatively deeper thanthe resistor 812.

FIG. 10 shows a depiction of the electric field dipole pattern 1000created by the antenna assembly 900 depicted in FIGS. 9A and 9B. Theelectric field dipole pattern 1000 is a donut pattern with the maximumstrength in the plane 1002 of the first and second loops 904, 906, withthe electric field polarization in the plane 1002 of the first andsecond loops 904, 906 (parallel to the current flow in the wire loop).With the IPG 10 placed flat in the patient's body such that the headerportion 11 and the ceramic case 14 are equidistant from the body surfaceor such that the plane 1002 of the first and second loops 904, 906 isperpendicular to the body surface, the maximum field is normal to thebody surface (outward) to achieve the best communication reliabilitypossible.

FIG. 11 is a flowchart illustrating one embodiment of a process 1100 formanufacturing a communication module and for wireless communication ofdata between an implantable neurostimulator and an external device. Theprocess 1100 begins at block 1102, wherein a transceiver is selected. Insome embodiments, the transceiver can be selected according to one orseveral desired parameters such as, for example, power consumption,output power, broadcast/receive frequencies, and/or the like. In someembodiments, the selection of a transceiver can correspond to theretrieval of a transceiver for assembly with an antenna circuit.

After the transceiver has been selected, the process 1100 proceeds toblock 1104, wherein the antenna circuit is created. In some embodiments,this can include the creation of the PCB, including the embedding of thecopper traces of the radiating element in the PCB, the attaching of thecapacitors and/or resistors to the PCB, and the attaching of one orseveral connectors to the PCB. In some embodiments, the creation of theantenna circuit can further include the tuning of the antenna circuit,and specifically, the tuning of the bandwidth of the antenna circuit toencompass frequency shifts arising from the implantation of the antennacircuit into the body of the patient. In some embodiments, thisbandwidth can be selected based on data gathered from one or severalpatients that is indicative of the statistical distribution of thefrequency shifts arising from the implantation of the antenna circuit inthe patient's body, and the selection of a bandwidth that will encompassall, or some percentage of the statistical distribution. In someembodiments, this percentage can include, for example, at least 50percent of the statistical distribution, at least 60 percent of thestatistical distribution, at least 70 percent of the statisticaldistribution, at least 80 percent of the statistical distribution, atleast 90 percent of the statistical distribution, at least 95 percent ofthe statistical distribution, at least 97 percent of the statisticaldistribution, at least 98 percent of the statistical distribution, atleast 99 percent of the statistical distribution, at least 99.5 percentof the statistical distribution, at least 99.9 percent of thestatistical distribution, and/or any other or intermediate percent ofthe statistical distribution.

After the antenna circuit has been created, the process 1100 proceeds toblock 1106, wherein the antenna circuit is connected to the transceiver.In some embodiments, this can include the connection of the first andsecond terminals of the transceiver to portions of the antenna circuit,such as is depicted in, for example, FIG. 8. In some embodiments, thetransceiver can be connected to the antenna circuit via a flexconnector, or via any other electrical connection.

After the antenna circuit has been connected to the transceiver, theprocess 1100 proceeds to block 1108, wherein the pulse generator isassembled. In some embodiments, this can include the assembly of the IPG10, and can include the connection of the communication module, andspecifically the connected transceiver and antenna circuit to one orseveral other components of the pulse generator.

After the pulse generator has been assembled, the process 1100 proceedsto block 1110, wherein the pulse generator is implanted. After the pulsegenerator has been implanted, the process 1100 proceeds to block 1112,wherein data is received at the pulse generator from the external devicevia the communications module, and specifically via the antenna circuitand the transceiver. In some embodiments, this data can be received atthe transmission frequency, which transmission frequency can be withinthe bandwidth of the antenna circuit at one or both of the first andsecond resonant frequencies. In some embodiments, this data can be usedto control and/or modify control of the pulse generator. Further, insome embodiments, the receiving of data via the antenna circuit canfurther include the transmission of data via the transceiver and theantenna circuit.

In the foregoing specification, the invention is described withreference to specific embodiments thereof, but those skilled in the artwill recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention can be usedindividually or jointly. Further, the invention can be utilized in anynumber of environments and applications beyond those described hereinwithout departing from the broader spirit and scope of thespecification. The specification and drawings are, accordingly, to beregarded as illustrative rather than restrictive. It will be recognizedthat the terms “comprising,” “including,” and “having,” as used herein,are specifically intended to be read as open-ended terms of art.

What is claimed is:
 1. An implantable neurostimulator for delivering oneor more electrical pulses to a target region within a patient's bodyaccording to a program received via wireless communication with anexternal device, the implantable neurostimulator comprising: a hermetichousing having an external surface comprising a biocompatible materialthat is configured to be implanted within a body of a patient; atransceiver disposed within the hermetic housing and comprising a firstlead and a second lead; and a communication antenna circuit disposedwithin the hermetic housing and coupled to the first lead and the secondlead, the communication antenna circuit comprising a printed circuitboard (PCB) having a first path and a second path parallel to the firstpath, the first path comprising a first capacitor, and the second pathcomprising: a second capacitor; a radiating element comprising aplurality of conductive loops; and a resistor, wherein the secondcapacitor, the resistor, and the radiating element are arranged inseries.
 2. The implantable neurostimulator of claim 1, wherein theplurality of conductive loops are located along a common plane of thePCB.
 3. The implantable neurostimulator of claim 2, wherein theradiating element crosses another portion of the second path.
 4. Theimplantable neurostimulator of claim 3, wherein the common plane of theradiating element is located at a different depth in the PCB than theother portion of the second path crossed by the radiating element. 5.The implantable neurostimulator of claim 3, wherein the radiatingelement comprises a necked down portion, wherein the radiating elementcrosses the other portion of the second path via the necked downportion.
 6. The implantable neurostimulator of claim 3, wherein theconductive loops comprise copper traces embedded onto a substratesurface of the PCB, and wherein the copper traces are configured toproduce an electric field dipole having a donut pattern with a maximumstrength in the common plane such that a maximum field is substantiallynormal to a body surface of the patient when the hermetic housing isimplanted for use.
 7. The implantable neurostimulator of claim 6,wherein the plurality of conductive loops comprises a first loop and asecond loop, wherein the second loop is located within the first loop.8. The implantable neurostimulator of claim 7, wherein the communicationantenna circuit has a fixed natural resonant frequency, the firstcapacitor has a first fixed capacitance and the second capacitor has asecond fixed capacitance.
 9. The implantable neurostimulator of claim 8,wherein the communication antenna circuit is defined by a Q factor andthe resistor is configured to diminish the Q factor of the communicationantenna circuit such that a bandwidth of the communication antennacircuits encompasses patient implantation-related variability inresonant frequency when the communication antenna circuit is implantedin the patient body and communicates with the external device.
 10. Theimplantable neurostimulator of claim 8, wherein the fixed resonantfrequency corresponds to a transmitting frequency at which theimplantable neurostimulator is configured to receive one or morewireless communications, and wherein the communication antenna circuithas a bandwidth such that an effectiveness of the communication antennacircuit at receiving the transmitting frequency does not drop below ahalf-power point of the communication antenna circuit when implantedwithin the body of the patient.
 11. The implantable neurostimulator ofclaim 1, further comprising a charging coil assembly comprising: a core;and a charging coil wound around the core.
 12. The implantableneurostimulator of claim 11, wherein the communication antenna circuitis positioned between the charging coil assembly and an end of thehermetic housing.
 13. The implantable neurostimulator of claim 12,further comprising at least one bumper extending from the communicationantenna circuit and towards the end of the hermetic housing.
 14. Amethod of wireless communication between an implantable neurostimulatorand an external device, the method comprising: receiving data at atransmission frequency with a communication antenna circuit of theimplantable neurostimulator from the external device, the communicationantenna circuit having a first resonant frequency corresponding to thetransmission frequency when the implantable neurostimulator is ex vivoand a second resonant frequency when the implantable neurostimulator isin vivo, the communication antenna circuit disposed within a hermetichousing of the implantable neurostimulator and comprising a printedcircuit board (PCB) having a first path and a second path parallel tothe first path, the first path comprising a capacitor, and the secondpath comprising: a second capacitor; a radiating element comprising aplurality of conductive loops; and a resistor, wherein the secondcapacitor, the resistor, and the radiating element are arranged inseries, and wherein the communication antenna circuit has a bandwidthsuch that an output power of the communication antenna circuit at boththe first and second resonant frequencies is greater than the half-powerpoint of the communication antenna circuit; controlling the implantableneurostimulator according to the received data; and transmitting data atthe second resonant frequency via the communication antenna circuit. 15.The method of claim 14, further comprising delivering at leastelectrical pulse to a target tissue via at least one stimulation leadaccording to the control of the implantable neurostimulator.
 16. Themethod of claim 15, further comprising delivering a first electricalpulse to the target tissue via the at least one stimulation lead beforereceiving the data.
 17. The method of claim 16, wherein the radiatingelement comprises a plurality of conductive loops located along a commonplane of the PCB.
 18. The method of claim 17, wherein the radiatingelement crosses another portion of the second path.
 19. The method ofclaim 18, wherein the common plane of the radiating element is locatedat a different depth in the PCB than the other portion of the secondpath crossed by the radiating element.
 20. The method of claim 18,wherein the radiating element comprises a necked down portion, whereinthe radiating element crosses the other portion of the second path viathe necked down portion.
 21. The method of claim 17, wherein, duringtransmitting data, the communication antenna circuit is configured togenerate an electric field dipole having a donut pattern with a maximumstrength in the common plane such that a maximum field is substantiallynormal to a body surface of a patient when the hermetic housing isimplanted for use.
 22. The method of claim 14, further comprising:receiving energy with a charging coil assembly of the implantableneurostimulator; and recharging a battery of the implantableneurostimulator with the received energy.
 23. The method of claim 22,wherein the charging coil assembly comprises: a core; and a chargingcoil wound around the core.
 24. The method of claim 23, wherein thecommunication antenna circuit is positioned between the charging coilassembly and an end of the hermetic housing.